Metal spray gun



May 5, 1942- F. o.' ALBERTSQN l 2,282,214

METALYSERAY GUN Filed July e, 1957 Patented vMay 5, 1942 METAL snaar GUN Frm o. Albertson, sio'x city, Iowa., mimo: to Albertson & Company, Inc., Sioux City, Iowa, a corporation of Iowa Application Jury 6,1931, serial No. 152,104

7 Claims.

The present invention relates to metal spray guns, and is particularly concerned with.i improvements in metal spray guns of the type covered by my prior Patent No. 2,058,653, issued April 30, 1936, and my prior application, Serial No. 143,718, iiled May 20, 1937, for Metal spray gun. The presentl application is a continuationin-part of my prior application, Serial No. 143,718, led May 20, 1937, for Metal spray gun.

One of the objects of the present invention is to provide an improved metal spray gun which will be kept at proper starting temperature b'y thermostatic control and which is adapted to give instant heat when the solder is inserted and melted in the metal well at the nose of the gun, and which is also adapted to boost the heating temperature as soon as the gun begins operating.

in a thermostatically controlled metal spray gun not having the features of the present invention, the nose of the gun cools on rst, as soon as the operator starts melting solder. It takes some time before this cooling effect travels to the thermostat, and therefore the gun is apt to cool too quickly as soon as solder is applied to it.

Another object of the present invention is to apply an instant supply of additional heat to the gun as soon as the gun starts to melt solder, so that the gun will not'get too cool and will be maintained at a proper temperature for melting solder.

Another object of the invention is to provide an improved metal spray gun adapted to be con trolled by a thermostatic switch so as to prevent heat damage to the gun, and in which the thermostatic switch is so arranged that the gun temperature at which it is actuated is changed when the gun is actually being used and the air is turned on, so that the gun may be kept at one temperature when it is idle but ready, and at another predetermined but higher temperature when the gun is actually being used.

Another object of the present invention is theV provision ofa thermostatically controlled and air cooled spray gun vof the class described, in

which the air supply is used to cool the thermo,`

stat so as to cause an immediate closure of the thermostatic switch when the gun is put in actual operation, to give instant heat at that time vand to raise the operating temperature a predetermined amount while the gun is in operation.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawing, in

which similar characters of reference indicate similar parts throughout the several views.

Referring to the single sheet of drawings, y Fig. 1 is a vertical sectional View, taken on a vertical plane passing through the axis of the air nozzle and the axis of a metal well, showing the details of construction or? the aun; y

Fig. 2 is a bottom plan view of the thermostatically operated control switch, taken on the plane of the line of Fig. i;

Fig. 3 is a yfragmentary vertical sectional view of the thermostatic switch, taken on the plane of the line 3 8 of Fig. 2, looking in the direction of the arrows;

Fig. fi is a vertical sectional view, en on the plane of the line of Fig. 2, looking in the direction of the arrows, showing further details of construction of the thermostatically operated switch.

Referring to the drawing, no aromates in 'its entirety the metal spray gun, which is provided with a handle t? for the purpose of supporting the gun during its operation.

The proper preferably comprises a rear body portion il` and a. forward body portion i3, these body portions being separated from each other by a pluralityl of projecting lugs i3 carried by one or the other of said body portions to reduce the conduction of heat between the bodies to a mum.

The body it preferably houses an air conduit lli, which may be connected by the usual ttings, and an air hose ib, to a supply of air under pressure. The conduit itis controlled by an air valve it, which is spring pressed to closed position, but may be opened by means of a push rod Il actuated by a trigger l@ carried by the handle 9. 'I'he air conduit it communicates with the air tube it, which begins in the body II and extends through the body i2, terminating in an arcuate air nozzle 2b.

The air tube it supports the porcelain body Ri, which carries the helically coiled and wrapped electric heating element 22. The body i2 may be of substantially inverted trough shape, the open side being closed by the lower cover plate 23,

secured in place by a plurality of screw bolts.`

The left end of the body i2 is provided with'an upwardly extending nose formation 2 4, provided with a tapered bore 25, which forms a metal `tending flanges 42,

.coil spring, as shown erably four in number, and'located at the four' l0 corners of the upper supporting body 26 of the handle. The supporting post 26 may be provided with a multiplicity of spacer rings 36 and heat radiating fin plates 3| carried by the posts,

and a multiplicity of other rectangular plates 32 l5 may be mounted on the same posts in spaced relation to each other for radiating heat which might beconducted to them from the upper hot body of the gun.

The major portion of the heat which is transferred to the posts 23, uns 3|, and plates 62 is thus dissipated by radiation, due to the increased radiating area of the plates and iins.

rThe trigger i8 is pivotally mounted at 33 on the handle 9 by means of the bracket 36. The 125 body 26 of the handle 6 supports a `bracket plate 35, which in turn supports a second bracket plate 36, upon which the trigger E6 is mounted. The push rod l1 is slidably mounted in a multiplicity' of aligned rectangular apertures in the plates 32, v3f) and its end rests upon a cross pin 31, which is carried by two rearwardly projecting anges 38, forming a part of the trigger I8.

Each end of the cross pins receive the hooked end of a 39, each o f which is provided with initial tension by having its lower end hooked to a part carried by the bracket 36. Thus the springs 36 urge the trigger i6 to the position'of Fig. 1. `When the trigger i8 is pulled, wise direction on the pivot 33, and moves the pin 31 upward, which moves the push rod i1 to engage the flange i6 and open the valve in the conduit I4.

31 is grooved to The lower reduced end of the push rod ,31 is 5 also conned behind a plungerpin di, which is slidably mounted upon a pair of rearwardly excarried by the bracket 36. The plunger pin 4I has 'a cylindrical head 42 which projects from and the plunger pindl is urgedl outward by a in my prior patent.

The trigger flange 38 has a shoulder d3, which may be caughtbehind the pin 4I when the button 42 and trigger i8 are simultaneously pressed.A 55

This latches the trigger i8 in such a position that the valve 16 is partially opened, thus permitting the air to leak past the valve to effect a cooling .of the gun, as described in my prior patent.

All of the details of the metal spray gun sol C() far described may be substantially as described l in my prior Patent No. 2,058,653, the description of which is hereby incorporatedby reference thereto, although I Adesire it to be understood that the features of the invention may also be 65 used .in'guns of differing construction ariddit'-` ferent appearance.

Thel closure plate 23 of the gun body l2 preferably supports a thermostatically actuated 48 engaging the plate 23. Plate 46 may be se- 75 cured to plate 23 by a plurality of screw bolts 49 which pass through the body 46 and are threaded into the plate 23,

.The plate 46 is provided with a centrally located enlarged bore 50 for passing freely a plunger 5l, which is actuated by means of a thermostat 52.

helical coil spring 23 it pivots in a counterclock-y 40.

ductor cable 66.

the side of the handle 9,' '55) switch mechanism, indicated in' its entirety by 70 The thermostat 52 preferably comprises a bimetallic thermostat of the dished type, that is, a metal member which is provided by joining together the two dished plates 53, 54, which may be of disc shape. The metal plate ,156 has a greater coefficient of thermal expansion than the metal plate 53, and when the thermostat 52 is heated the plate 54 expands more than the plate 53, and tends to reverse the curvature of the thermostat 52, as shown in Fig; 3. This tendency.

of the thermostat 52 is resisted by .the dished formation of the disc; and consequently,there is a critical point at which the thermostat changes its curvature, to actuate the switch plunger 5l.

The thermostat 52 is provided with a centrally located aperture, Awithin which the end of the plunger 5i issecured, as shown. The thermostat 52 is supported at its edges by having its edges located in the grooves 55 of a plurality of metal posts 56, four innumber, which are located at equally spaced points disc thermostat 52, cured in the plate body d6 by means of reduced cylindrical portions which are riveted over at 51. The plate body 66 also supports a plurality of contact members 58, 56, 66, and 6I, which are insulated from' the plate by. a sheet 62 of insulation, preferably mica, so that it will be able, 4to withstand the temperatures. .The contacts 56 and are connected to the terminal posts 63, 66., One lead from the terminal post 63 may be connected to one terminal of the heating element 22. The other terminal of the heating element 22 may be connected to the outgoing concontact 66 may be connected to the outgoing conductor cable 66.

The two contacts 58 and 6I may be supported upon the metal posts 68, 69, all of which are insulated from the plate 46, and the posts 68, 69 are joined by a conductor 10, in the present case. Thus the contacts 58-61 are in series with the heating element 22,'and may be energized from the line cable 66 when .the contacts 58 and 59 are bridged andthecontacts 60 and 6I are simultaneously bridged.

The thermostat plunger 5i has its lower end (Fig. 3) adjustably connected by means of the threaded portion 1l and the nuts 12 to a metal plate 13. The metal plate .13 (Fig. 4) supports a pair of bridging contacts, comprising the Ametal discs 14, 15. These contacts are each loosely and substantiallyuniversally mounted on a'metal plate 13 by the following arrangement:

A metal supporting stud or riigetr 16 is provided with a collar 11, having a partially spherical surface 18. The collar 11 and stud 16 are riveted on the plate 13, suitable insulating washers being disposed between the collar and the washers and the stud 16 being spaced from the aperture in the plate '13. The riveted endj 19 of the stud forms a head below which is mounted the bridging contact 14 in the form of a disc. The contacts 58 and 59' are spaced sufliciently'so. that' they are not engaged by the rivet head 19, but they are engaged by the disc 14. The disc 14, being loosely mounted below the head 19 on the partially spherical surface 18, the disc 14 has a.

about the periphery of the The metal posts 55 are sef The other lead 61 from the limited universal movement and is adapted to nd the proper position, engaging both the contacts 58 and 59.

The thermostat plunger I is thus adapted to move both the contacts 14, down simultaneously and open the circuit at two places when the thermostat is heated to a predetermined de gree. The point at which the thermostat opens is critical, and it may be so arranged as to keep the gun at a temperature of 560 to 600 degrees F. at the metal well when the gun is under thermostatic control. In the event the plunger 5I tilts slightly, it will nevertheless open one of the contacts 'I4 or'15, although the other one may be closed, and thus the opening of the circuit by the thermostat is assured, irrespective of the fact that the thermostat plunger 5I may be slightly tilted when the thermostatic switch is in open position. The thermostatic switch is preferably enclosed in a cup-shaped housing 80, which surrounds the switch structure and the leads and is provided' with an attaching flange BI secured .to the plate 23 by a plurality of screw bolts.

The present metal spray gun is also provided with means for rendering the thermostat ineffective whenever the gun is under operation. This means comprises Ithe cooling elect ofair which is conducted to the thermostat whenever there is a back pressure in the air tube I9. Forv this purpose the body I I of the gun may be provided with u a backwardly extending bore 82 for receiving a backwardly turned end of an air tube 83.

The air tube 83 extends along, under the body II, and under the porcelain support 2I for the heating element 22, andterminates in a downwardly extending nozzle 84, which extends through an aperture 85 in the plate 23, into the chamber 86 of the thermostatic switch housing 8U.

Referring to Fig. 3, it will be noted that the.

nozzle 84 isl directed towardthe thermostat 52.

The operation of the metal spray gun lsas follows: The electric heating element 22 is energized by connecting the plug, which is at the end of the cable 66, to a standard 110 volt A. C. or D. C. lighting circuit. The thermostatic switch is normally closed, as shown, in Fig. 4, and therefore the current may pass directly through the circuit, which includes the switch and heating element.

The gun is then heated up, and as soon as it reaches a predetermined temperature, the heat, which is transferred to the thermostat 52 by contime by the tube 83 to the thermostat 52. When the operator uses the gun, however, he pulls the trigger I8 back fully, to provide a full supply of air under pressure, and a back pressure is created in the pipe I9. Then air is conducted by the pipe '83 to the thermostat 52, and in a very short time mostat does not become ineffective, but it resumes control of the gun at, for example, about 759 degrees, so that the temperature of the gun never exceeds that point. When the gun is ready for operation but not being used, the thermostat is adapted to function at a temperature of approxivection, conduction, and radiation, raises thev thermostat to such a point that lt-reverses its curvature from that shown in Fig. 4 and opens the contacts. The gun is then at the proper operating temperature, and should it cool to a predetermined degree, the thermostatic switch will then again turn on the current, and the gun will be maintained at proper. operating temperature until the operator is ready to use it.

It is advisable at this time to pull vthe trigger IB and latch it by means .of the plunger pin 4I `so that the air under pressure,whlch is carried by the hose I5 tothe gun, is permitted to leak past the valve I6 into the tubelii through the gun. This effects a cooling of the interior of the gun and prevents damage to those parts of the gun which might otherwise become too hot, because there is no opportunity for radiation from the parts in the interior of the gun.

The leakage of air past the valve I6, however, does not produce any back pressure in the air tube I9, and little or no air is conducted at this mately 600 degrees F., which is a suitable temperature for beginning operations.

'Ihe present gun employs a relatively large heating element, such as, for example, a 900 watt element, which furnishes ample heat for the gun under continuous operation. With the present thermostatic arrangement, the gun has two temperatures: one temperature at which it is maintained When ready but not operating, and another teniperature at which it is maintained when actually melting solder. The air supply is utilized to change the characteristics of the thermostat with respect to the body of the metal spray gun.

Thus, while the gun is maintained under thermostatic control, it is kept at a higher temperature lwhen it is actually operating and melting solder. 'Ihere is no possibility that the present gun will be damaged, since it is protected at al1 ltimes against over-heating, by the action of the thermostatic switch.

It will thus be observed that I'have invented an improved metal spray gun which is protected by a thermostatic switch, so that the gun cannot be over-heated at any time. As soon as the gun' is placed under operation, the thermostatic switch and air pipe `arrangement provide an instantaneous supply of additional heat, for the melting of solder. The gun temperature is boosted .as soon as the gun starts operating. The gun is then maintained atproper operating temperature for melting solder; but as soon as the gun is not actually in use, the air supply to the thermostat is cut out, and the thermostat functions at a normal temperature of approximately 600 degrees F.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

l. In a metal spray gun, the combination of a metal body provided with a metal well, an air nozzle carried by said body, a source of heat for said body comprising an electric heating element, thermostatic means for controlling said heating element, and means tending to cool said thermostatic means when the gun is operated, said thermostatic means being eiective at one temperature during the operation of the metal spray gun, and at another temperature when the gunis hot but not operating.

' 2. In a metal spray gun, the combination of a metal body provided with nozzle carried by said body,

va metall well, an air a source of heat for said body comprising an electric heating element,

and thermostatic means for controlling said heating element, said thermostatic means being eiecthe thermostat is subjected to cooling `air .when

the gun is under operation.

v3. In a metal spray gun, the combination of a metal body provided with an electric vheating element and having a metal well and an air nozzle, a thermostatic switch connected vin circuit with said electric heating element and adapted to control the energization of said heat# ingelement, said thermostatic switch being connected to said metal body to receive heat from said metal body by radiation and conduction and means for changing the operationof said thermostatic switch when the air pressure is created in said air'nozzle during the operation of the gun, said means comprising an air-conduit in communication with said air nozzle and adapted 4to be provided with a supply of air due toback' pressure in said nozzle, said air conduit conducting cooling air to the thermostat of said y switch.

' 4. In a metal spray gun, thel combination of a. metal body provided with an velectric heating element and having a metal `well and an air nozzle, a thermostatic switch connected in cir- Y cuit with said electric heating element and handle for/supporting said second body, and

Vmeans for securing said handle to the second body, comprising a plurality of posts and spaced plates carried by said posts forradiating heat, an air tube carried by said bodies, said air tube having one end communicating with a'tting adapted to be attached to a source of air under gun being provided with an air control valve, and

means for manually controlling the actuation of said air controlvalve.

5. Ina metal spray gun, the combination of an electric heating element with a metal spray` gun, thermostatic switch means carried by said spray gun for controlling the energization of said electric heating element, and means for affecting the operation of said thermostatic' switch means comprising a supply of cooling air under pressure directed on the thermostat wherebythe circuit to the heating element will be broken only at a higher predetermined temperature when the metal spray gun is in operation. i 6. In a metal spray gun, the combinationv of a metal body provided with a well comprising a downwardly tapered bore having a'nozzle opening for .receiving metal and discharging it after it is melted; said body housing an electric heating element, la second metal body lfor supporting pressure, and having the other end 4formed with an arcuate nozzle aperture, said arcuate nozzle aperture being arranged to discharge airin the form of a trough beneathv the point of discharge of melted metal from said well, and thermostatic means comprising a thermostat, and an electric switch actuated thereby, Asaid switch being connected in series with said electric heating element for cutting oit the electric current at a predetermined temperature, whereby the overheating of the metal well and the burning of the metal to be melted .is prevented, and manual means for controlling the operation ofsaid thermostat and rendering the thermostat ineffective to open the switch in circuit with the electric heating element except at a predetermined higher temperature when the gun is operating. f

7. In a metal spray gun, the combination of a metal body provided witha well comprising a downwardly tapered'bore having a nozzle opening for receiving metal and discharging it after it is melted, said body housing an electric heatingelement, a second metal body for supporting the first-mentioned metal body, said second body having a plurality of points of attachment, and having the major portion of its adjacent surface out of contact with the first-mentioned body, a

handle for supporting said second body, and

means for securing said handle to the second `body, comprising a plurality of posts and spaced plates carried by saidposts for radiating heat,- an air tube carried by said bodies, said air tube having one end communicating with a fitting adapted to be attached toa source ofair under pressure, and having the other end formed with an arcuate nozzle aperture, said arcuate nozzle aperture being arranged to discharge air in the I form of a trough beneath the point of discharge of melted metal from said well, and thermostatic. means comprising a thermostat, andan electric switch actuated thereby, said switch being connected in series with said electric heating element for cutting oil the electric current at a predetermined temperature, whereby the overheating ofthe metal well and the burning of the metal to be melted is prevented, and manual means for controlling the operationof said thermostat and rendering the thermostat'ineffective to open the .switch in circuit with the electric heating element except at a predetermined higher temperature when the gun is operating, said `manual means including a trigger-operated air valve interposed in the air pressure line to the air tube, and said gun including means communicating with Athe air tube for blowing air on said thermostat when said valve is opened.

FRANS O. ALBRTSON. 

